Reed mechanism



July 18, 1933. w, c, R 1,919,041

REED MECHANISM Original Filed June 7, 1930 x xxx xxxxxxxxxxx INVENTOR.

M'lljam C. Hoe

my?! WJ A TTORNEY.

Patented July 18, 1933 UNITED STATES 1,919,041 PATENT OFFICE WILLIAM C.ROE, OF ELYRIA, OHIO, ASSIGNOR TO TELKOR, INQ, OF ELYBIA, OHIO, ACORPORATION OF OHIO REED MECHANISM Original application filed June 7,1980, Serial No. 459,674, now Patent No. 1,854,863, dated April 18,1982. Divided and this application filed September 8, 1931. Serial No.561,614.

My invention relates to reed mechanisms and relates more particularly toimprove ments in vibratilereed circuit controllers for electricalsystems.

My invention relates to that eneral type of vlbratile'reed circuitcontrol er disclosed in my prior Patent No. 1,646,662, dated October 25,1927, the present application disclosing improvements to the method andapparatus shown in my aforesaid prior patent, and my copendingapplicatlon for United States Letters Patent caring Ser1al No. 459,674,filed June 7. 1930, now'Patent No. 1,854,863, issued April 19, 1932 for?Reed convertors and methods, of which this is a divisional application.

An object of my invention is telprovide an improved synchronous reedmechanism Another object of -my present invention is to provide animproved reed controller for use in translating a periodically varyingcurrent into periodically varying current impulses of a differenteffective frequency. f "Another object of my invention is to provide animproved reed operated circuit-controller adapted for use to morecontinuously utillz'e 'the su 'plied current impulses in the translationsaid impulse into current im- P S 'Which periodicallyvary at arelatively fractional rate. v

Another object of my invention is to provide an improvedsynchronolisreed controlled current flow inodifie1 Other objects of myinvention and the invention itself will become apparent by reference tothe following description of an embodiment of. my invention illustratedmore or figures of drawing, wherein: p

F ig.v 1 is a side elevational view of an electro-magnetic reedcontroller 'employed'in an embodiment of my invention Fig. 2 is anelevational view of the reed for the controller of Fig. 1';

Fig. 3 is a diagrammatic view of a system employing the controller ofFig. 1;

Fig. 4 is a side elevational view of a controller employing incombination the struc ture of Figs. 1 and 2, together with an additionalreed and circuit controlling contacts.

Fig. 5 is a medial longitudinal section relatively enlarged of afragment of the controller of Fig. 4;

less diagrammatically in the accompanying plied current wave andsuccessively disposed therebelow, impressed and resultant current wavesresulting from the operation in electrical iystems of the apparatus ofthe foregoing gures.

Referring now first to the reed a paratus of Figs. 1 and 2 and thesystem of l 3, in which the said reed apparatus may e employed, at 1 Ishow an electromagnet having a core terminating magnetically in'laterally extending pole pieces 2 and 3 at its respective two ends.

The pole piece 2 terminates in a pole flange 4 and the pole iece 3terminating in a pair of inturned forlis 5 and 6.

At 7 I show a com ound reedialement comprising a pair of leai springsSand 9 secured together by a pair of rivets 10 and an intermediate rivet11 forming an electrical contact point as will later-appear. The two "byend portions so that when secured together the effect of the spring 91isto form a resilient extension for the spring 8 whose end 12 extendstoward the free end of the 9 to a point approximately mid-way of theends of said sprin The spring 8 is provided with a pair 0 perforations13 adapted to admit the shanks of rivets 14 projected therethrough, andthrough aligned perforations of a metallic block 15'j-and of the fork 6of said electromagnet pole": iece, whereby the compound reed 7 is rigidy imounted on said fork.

The spring 9 carries an inertia weight element 16 which, in the-form ofa looped strip of metal 17, embraces the spring 9 and to which there isrotatably secured an ad'ustable arm 18 pivoted to the freeends o theloop 17 by a rivet 19 securing the free ends of the loop and an end ofthe arm together in such a manner as to clamp the loop onto the springand to form a pinion on which the arm 18 may frictionally rotate inorder sprmg to adj ustably dispose its free end moreor less The reed asmounted on the electromagnet tructure of Fig. 1 is disposed with thespring 9 innermost, that is, towards the electromagnet 1, and thecontact 11, heretofore referred to as a rivet, projects outwardly toengage the contacting end of a contact screw 2] which is adjustablyscrew-threaded in an insulating bushing 22 carried by an end of the fork5 of the pole piece 3.

When the screw 21 is turned in the bushing to advance its point intocontact with the contact 11, an electrical circuit is completed betweensaid screw and said contact and when the electrical circuit of Fig. 3 iscomplete, including said contact screw 21 and contact 11, the compoundreed is thrown into vibration under the control of the contacts 11-21 ata rate dependent upon the inherent properties of the reed, theelectrical and mechanical effect of the engagement of the contacts andthe strength of the magnetic field in which the steel compound reed isoscillated, but under the dominant control of the impulses of electricalcurrent supplies from a source such as the alternating current generator23 over the circuit conductors, as illustrated in Fig. 3, the circuitof-which will now be explained.

Referring now particularly to Fig. 3, wherein an electrical systemsimilar to that disclosed in my copending application for Letters Patentis shown employing the reed of my invention, at 24 an alternatingcurrent transformer is illustrated comprising a primary winding P and asecondary winding of any desired transformation ratio, such as forinstance 1 to 1. The secondary winding S is extended by circuitconductors 25 to any desired electro-responsive devices adaptable foroperation by the current derived from the mechanism and circuitdescribed, such as the telephone, polarized bells 26, shown as beingconnected across the conductors 25, each in series with an appropriateelectrical condenser 27.

The winding of the electromagnet 1 15 connected in serial circuit withthe source of alternating current. 23 and the contacts 21 and 22, andthe primary winding 1, in the embodiment illustrated, is shown asconnected in multiple with the winding of the electromagnet 1.-

The system of Fig. 3 operates as follows: Alternating current having theapproximate wave form of that indicated at A in Fig. 9, being suppliedfrom the source 23 to the winding of the 'electromagnet 1 through the'pontacts 2111, Fig. 3,-- Will energize the electromagnet to cause theend of the reed 7 to approach the pole piece flange 4, as indicated bythe dotted lines 28, Fig. 1, at the same time effecting breaking of thecircuit by separation of the contacts 21-11. The contacts being broken,the reed by the power of its,own inherent resiliency will retract toagain close the contacts with the foregoing result repeated.

\Vhen so oscillated, the reed constructed as illustrated in Figs. 1 and2 will oscillate within the limits relatively substantially as shown bythe dotted lines 28 and 29 to periodically make and break the contact21-11. Due to the compound nature of the reed, the relative positioningof its parts 8 and 9 and mechanical engagement on the back strokebetween the contact 11 carried by the reed and the fixed contact 21, thereed will take a longer excursion toward the pole flange 4 than in theopposite direction, and by suitable adj ustment of the screw 21 whilethe reed is vibrated, each forward excursion of the reed will be causedto take just twice as long as each rearward excursion thereof. When thisresult is obtained, the fact will be visually evident to the one makingthe adjustment by noting that at such time the substantially completeabsence of electrical sparking at the contacts.

When this condition is secured, it is found that the reed is' vibratingby impulses of current taken from the wave such as shown at A, Fig. 9,and indicated in solid lines by the portions thereof shown at a and b,Fig. 9. In other words, as shown at B, the current impulses throu h theelectromagnet 1 are of alternate polarityand spaced from the nextsucceeding impulses of current by a full cycle of omitted impulses ofalternating current indicated 'by dotted lines between the impulses aand b. The solid line impulses a and b of successively opposite polaritypassing through the electromagnet 1 also pass through the primarywinding P of the transformer 24 with the result that an alternatingcurrentis supplied by the secondary winding thereof having a periodicityone-third that of the periodicity of current supplied by the source 23.The current wave produced by the compound reed of my present inventionis similar to that previously described in my prior Patent No.1,646,662. dated October 25, 1927, and in my copending application forUnited States Letters Patent bearing Serial No. 459,674, filed June 71930, and to which reference may be had.

In the apparatus of Fig. 1, the reenforcing portion of the spring 8,overlapping the spring 9 causes a resistance to be resiliently appliedto retractive movements of the spring 9, and particularly this is truewhen the contact screw 21 engages the contact 11 atlixed to the reed 7at a pointspaced from its support 6. On the forward excursion toward theposition 28, however, the overlapping portion ofthe spring 8 has no suchfunction and the spring 9 and the supporting portion of the spring 8swings freely inwardly, in a manner similar .to that which would occur,were the springs 8 and 9 one continual spring with no overlappingportion.

In effecting vibration of the compound reed at a rate which is exactlytwo-thirds that of the periodicity of the supplied alternating current,the arm 18 of the element 16 may e adjusted to varying positions byrotating it on the pin 19 until its periodicity corresponds to thefractional periodicity of the alternating current desired.

It will be understood that the tuning of the compound reed is to beaccomplished with a view to the frequency of alternating current desiredto be obtained by the operation ofthesystem and that the reed vibrationrate above given is that which would be required to be had where it isdesired to obtain an 'alternating current whose periodicity is onethirdthat of the periodicity of current from the source, as described herein.

In the embodiment of my invention illustrated in Fig. 4, the apparatusshown to the right of the longitudinal middle line :va: is like thatpreviously shown and described in connection with Figs. 1, 2, 3 and 9,and therefore this part of the apparatus of Fig. 4' will be referred tobut briefly in connection with the description of the operation of theapparatus shown to the left of the medial line .'ca: of Fig. 4, whereinthe pole pieces 2 and 3 of Fig. 1 are integrally prolonged toward theleft toprovide the pole tip 2 and the pole piece 3' bifurcated at itsend to provide the reed supporting arm 30 and the fixed contactsupporting arm 31. An elongated main reed 32 and ashort contact-carryingsupplemental reed 33 aresupported by an end of each, in relativelysuperposed relation on the arm 30 being clamped thereto bya plate 34 andrivets-'35 pro ected "through aligned apertures ofsaid plate, saidsuperposed reedsand said arm 30. 'Themain and supplemental reeds, perse, are respectivelyjillustrated in elevation in Figs. 6 and],whereint'he rivet receiving. apertures are shown and also are shown at36,. and also fan aperture 37 is shown provided in the supplemental feed33 for""the reception of the reduced ne'ck 38, Fig.5, of an electricalcontact element-39 in the formof-a rivet and, having a contact portionprojected from a flat side of the supplemental reed.

Also, an enlarged aperture 40, Figs. 5 and 6, is provided through whichthe projecting portion of the contact 39 may extend for engagement bythe contact point of the fixed contact screw 41, which is adj ustablymounted in. the insulating block or bushing 43 carried by the arm 31. I

The supplemental reed 33 being substantially shorter, less than one-halfthe-length, than the reed 32, terminates at a point 44 which lies butslightly beyond the contact 39 carried by it and being disposed on theouter side of the main reed 32, and engageable therewith on all outwardexcursions, such as indicated at 45 of the reed 32, restrains thecommutating the current through "t main reed in outward movements, thatis, when moving in directions away from the pole tip 2".

However, the presence of the reed 33 at first accelerates the inwardmovement toward the position 46 of the reed 32 and the inward swing ofthe reed 32, like the inward swing of the reed 9 is of much greater amlitude than the outward swing, as at 29, re erring again to the reed 9.

It is to be noted, however, that the positioning and relationship of thecontacts 39-41 is different from that of the contacts 11-21, and theadjustment of the contact screws is previously made so that when thereis engagement between the contacts 11 and 21, the contacts 40 and 39 aredisengaged and the contrary is also true, namely, that upon engagementof the contacts 39 and 40, there gvlill be disengagement of the contacts11 and The electrical circuit preferably employed for the embodiment ofFig. 4 is illustrated in Fig. 8, and is also illustrated in my copendingapplication for Letters Patent above referred to, and by referencethereto, it will be noted that current flow through the electromagnet 1is directl controlled by the contacts 1121, whereas t e contacts 39 and41 are employed in the circuit merely to control the flow of currentthrough one of two primary windings P2 of a transformer T having asecondary winding S and a second primary Winding P1.

The said second primary winding is connected across the terminals of theelectromagnet 1 and therefore both the electromagnet and the primarywinding P-1 is. always exposed to the same varying electro-motive force.The two contacts sets may be differentiated in that the contactset 11-21is both a motor controlling contact set and acurrent commutating contactset for the primary winding P-1, whereas the contact set 39-41 isintended principally for the pur ose of e. nmary winding P2. A pair ofconden ers 47 and 48 may be employed connected as shown in the circuitof Fig. 8 to more completely eleminate the tendency toward s arking,which may occur at the two sets oFcontacts where precise adjustmentsthereof and of the adjustable weighting elements 18 and 18 for the reeds9 and 32 respectively are not had.

In the electrical system of Fig. 8, the alternating current generator isshown at 23'. The electromagnet coil 1 is that of the apparatus of Fig.4, as are also the reeds 9, 32, and 33, and the respective contact setsthere,- for. The transformer is provided with two like primary windingsjoined'together at an end of each from which an electrical circuitconductor 49 extends to a pole of the source 23' of alternating current.The otherpole of the source of current leads by a conductor 50 tobranching circuit conductors which are electrically connected to thereeds 8, 9 and 33, the carried contacts of which are intermittentlyengaged, as before described by the fixed contacts 21 and 41,respectively.

When the respective circuits served by these contacts are closedthereby, alternately, as before related, current is alternately directedthrough-the primary windings P-1 and P-Q in the opposite directions, asindicated by the arrows shown between the primary and secondarywindings.

Referring now to Fig. 9, the effect of the operation of the apparatus,as previously described, and the electrical system of Fig. 8 in whichsuch apparatus is graphically shown therein. Fig. 9 is provided witheight representations of alternating current waves, there being shownboth impressed and resultant current waves and of these the uppermostwave A will be assumed to be the current wave ordinarily supplied from aenerator. such as that shown at 23 when a xed load is applied to thegenerator. It also represents the current wave supplied from the generator 23' to the electrical system illustrated in Fig. 8.

The current impulses which pass from the generator 23 through thecontacts 11-21, to the transformer having the primary winding P, arethose shown, in solid lines at a and b at B, Fig. 9, those at a being,we will assume, positive impulses, and those at b being assumed to benegative impulses. It is noted that the positive and negative impulsesare alternated with respect to time, which is taken as running from leftto right, Fig. 9, and that between each positive and each negativesuccessive impulse, there is omitted a complete cycle comprising twoimmediately adjacent negative and positive waves.

The effect of periodically omit-ting a cycle of current on the wave formof resultant current is approximately diagrammatically shown at C, themagnetic lag in the transformer'of the system and the inductance of thesystem itself, prolonging the impulses a somewhat.

Now the commutating contacts 39-41 of Figs. 4 and 8 effect periodicimpulses of'current each consisting of the dotted line, omitted cyclesof alternating current shown at B. Each of these cycles comprise, asshown at D, a negative impulse b and a positive impulse 11, immediatelysucceeding it, and between each cycle of impressed current suppliedthrough the contacts 39-41, as shown at D, there is omitted,successively, negative impulses b and positive impulses a at the timesas shown by the impulses b and a at B when such impulses are permittedto flow by the contacts 11-21.

The impressed current, shown at D, provided by the contacts 39-41 may beconsidered as being reversed in polarity, when supplied to thetransformer having the secondary winding S, with respect to suchsecondary winding, since current flow through the contacts 39-41 passesthrough the primary winding P-2 (see D) in a direction which is exactlyopposite to the direction of flow of impulses through the contacts 11-21(sec B), so that when considering such impressed current in connectionwith the impressed current through the primary winding P-1, and both inrelation to the effect on the secondary winding S, it is easier toconsider the impulses gs tiging in the reversed direction, as shown Byanalogy to the curve shown at C, relative to the impressed current, asshown at B, the wave form of the resulting current through the windingP-2 is probably much like that shown at F, since insufficient time isprovided between successive positive impulses and between successivenegative impulses for the current to decay to nullity.

Considering now the resultant wave forms C and F and the impressed waveforms B and E, respectively, the impressed wave forms of B and E beingcombined, provide a wave, as shown at G, wherein three immediatelyconnected positive impulses are immediately succeeded by threeimmediately connected negative impulses ad intinitum. Also thecombination of the resultant wave forms G and F provides a wave whichmay be more or less like that shown at H, although this showing isexaggerated to accentuate the tri le ripples at the crest of eachpositive and negative wave.

The wave H is that which is delivered by the secondary winding S, Fig.8, to the electro-responsive devices such as telephone bells 26', whichare serially connected across circuit conductors leading from the saidsecondary winding, each bell preferably being in series with anassociated condenser 27" in accordance with common standard practice.

Having thus described my invention in certain embodiments thereof, I amaware that numerous and extensive departures may be made from theembodiments herein illustrated and described, but without departing fromthe spirit of my invention.

I claim:

1. A vibratory reed construction comprising a pair of resilient reeds,the free end of one reed overlapping the free 'end of the other reed,and means ada ted to periodically communicate vibratory impulses to thefirst reed causing it to alternately engage-and disengage said secondreed, whereby the amplitude of the first reed is caused to be greater inone direction than in the other, and electric contacts controlled bymovement of the said. second reed.

2. A vibratory reed construction comprising a pair of resilient reeds,the free end of tacts controlled by the said second reed an inertiaelement carried on said first reed and adjustably movable longitudinallythereon to vary the periodicity thereof.

3. A reed mechanism for an electrical system comprising a main reed andasupplemental reed, means for sup orting corresponding ends of the mainand supplemental reeds in superposed relation, an electro-magnet mentalreed away from the free end of the main reed, the free end of the mainreed engaging an intermediate portion of the supplemental reed upon aretractile movement of the sup lemental reed following attractionthereof y said electro-magnet to restrain the movement of thesupplemental reed in the retracting direction and an electricalcontact;v

element engageable with the main reed independently of the supplementalreed during the forward excursion of the supplemental reed.

4. A reed mechanism for an electrical system comprising amain reed and asupplemental reed, means for supporting corresponding ends of the mainand supplemental reeds in superposed relation; an electro-magnet adaptedto periodically draw the supplemental reed away from t e free end of themain reed, the free end of the main reed engaging an intermediateportion of the supplemental reed upon a retractile movement of the sulemental reed following attraction thereof y said electro-magnet torestrain the excursion of the supplemental reed in the retractingdirection and an electrical contact element engageable with the mainreed independently ofthe supplemental reed during the forward excursionof the supplemental reed, said contact restraining the main reed frommovement following the forward excursion of the supplemental reed.

5. A reed mechanism for an electrical sys tem comprising a relativelyshort main vi-' bratory reed, and a relatively long supplees. mentalvibratory .reed meains for support" ing corresponding endsof the mainand sup plemental reeds in superposed relation, an

alternating current magnet adapted tope riodically draw the-supplementalreed away from the free end oflthe main reed, the free end of the mainreed engaging an intermedi ate portion of the supplemental'reed upon aretractile movement of the supplemental reed following attractionthereof by said alternating current magnet to restrain the excursion ofthe supplemental reed in the retracting direction and electric contactscontroliled by vibratory movement of the main ree 6. A reed mechanismcomprising a relatively short main reed and a relatively longsupplemental reed, means for supporting corresponding ends of the mainand sup lemental reeds in superposed relation, an an clectro-magnetadapted to communicate impulses of magnetic force to the supplementalreed and to periodically draw the supplemental reed away from the freeend of the main reed whereby the amplitude of vibration of the main reedis rendered greater in one direction than in the other, and electriccontacts controlled by vibratory movement of the main reed. adapted toperiodically draw the supple .tem comprising a main reed, and a supple-7. A reed mechanism for an electrical sysmental reed, means forsupportin the supplemental reedcupon the main ree anelectro-magnetadapted to periodically draw the supplemental reed awayfrom the free end of the. main reed, the free end of the main reed--engaging 'an intermediate portion of the sup plemental reed upon aretractile movement of the supplemental reed following attractionthereof by said electro-magnet to restrain the excursion of thesupplemental reed in the retracting direction and an electrical contactelement engageable with a contact point on said main reed during the retractile excursion of the supplemental reed.

8. A reed. mechanism for an electrical system comprising a main reed,and a supplemental reed, means for supportin the supplemental reed uponthe main ree an elec' tro-magnet adapted to periodically draw thesupplemental reed away from the free end of the main reed, the free endof the main reed engaging an intermediate portion of the supplementalreed upon a retractile movement of the su plemental reed followingattraction thereo by said electro-magnet to restrain the excursion ofthe supplemental reed in the retractile direction andan electricalcontact element engageable with :.all-contact point on said main reedduring the, retractile excurscion. of the supplemental reed; contactbein broken upon the forward, excursion there'o 9 5A reed mechanismfogan {electrical sysmentaliree upon ithestmain reed, anelectromagnetjadapted to periodi'eallydraw the supplemental reeda'vvay-E froinflthe free end of the mainireeditheQfree'fendQf themainreed engagingan intermediate 'portionof the sup plemental reed upom aretractile movement of the supplemental reed following attractionthereof by said electro-magnet to restrain the excursion ofthe'supplemental reed in the retractiledirection and an electricalcontact element engageable with a contact point on said main reed duringthe retractile excursion of the supplemental reed, contact being IIIbroken upon the forward excursion thereof, the forward excursion of saidsupplemental reed being of relatively longer periodicity than saidretractile excursion.

10. A vibratory reed mechansm comprising a relatively short mainVibratory reed, and a relatively long supplemental vibratory reed, meansfor supporting said supplemental reed upon the main reed. anelectro-magnct adapted to communicate impulses of magnetic force to thesupplemental reed to periodically draw the supplemental reed away fromthe free end, of the main reed whereby the amplitude of vibration of themain reed is rendered greater in one direction than in the other, andelectric cont-acts controlled by vibration of the main reed.

11. A compound reed mechanism, each mechanism comprising amain reed anda supplemental reed, means for supporting the main and supplementalreeds in superposed relation. an electro-magnet adapted to period icallydraw each supplemental reed away from the free end of each main reed,the free end of each main reed engaging an intermediate portion of itssupplemental reed upon a retractile movement of said supplemental reedfollowing the attraction thereof by said electro-magnet and electriccontacts controlled by movement of the main reed.

12. A double reed mechanism, each mechanism comprising a relativelyshort main reed and a relatively long supplemental reed, means forsupporting corresponding ends of the main and supplemental reeds insuperposed relation. an electro-magnet adapted to periodically draw eachsupplemental reed away from the free end of each main reed, the free endof each main reed engaging an intermediate portion of its supplementalreed upon a retractile movement of its supplemental reed following theattraction thereof by said electro-magnet, the forward movement. ofeachof said supplemental reeds thereby caused to be of relatively longerperiodicity than said retractile excursion and electric congactscontrolled by movement of the main ree 13. A double reed mechanism, eachmechanism comprising a main reed and a supplemental reed, means forsupporting the main and supplemental reeds in superposed relation, eachmain reed overlapping and reenforcing its supplemental reed, anelectromagnet adapted to periodicallyvdraw each supplemental reed awayfrom the free end of its main reed, the freeend of each main reedengaging an intermediate portion of its supplemental reed upon aretractile'movement of its supplemental reed following the attractionthereof by said electro-magnet, said reenforcing main reed effecting aresistance to retractive movements of said supplemental reed in theabsence of magnetic impulses, the

forward excursion of each of said main reeds thereby caused to be ofrelatively longer periodicity than said retractive excursion andelectric contacts controlled by movement of the main reed.

14. A double reed mechanism, each mechanism comprising a relativelyshort main reed and a relatively long supplemental reed, means forsupporting corresponding ends of the main and supplemental reeds insuperposed relation, an clectro-magnet adapted to periodically draw eachsupplemental reed away from the free end of each main reed, the free endof each main reed engaged by intermediate portion of its supplementalreed upon a retractile movement of its supplemental reed following theattraction thereof by said electro-magnet, the forward movement of eachof said supplemental reeds thereby caused to be of relatively longerperiodicity than said retractile movement, an inertia element carried oneach of said supplemental reeds and adjustably movable longitudinallythereon to vary the periodicity thereof and electric contacts controlledby movement of the main reed.

16. A compound reed mechanism, each mechanism comprising a main reed anda. supplemental reed, means for supporting the main and supplementalreeds in superposed relation, an electro-magnet adapted to periodica-lly draw each supplemental reed away from the free end of eachmain reed, the free end of each main reed engaging an intermediateportion of its supplemental reed upon a retractile movement of saidsupplemental reed following the attraction thereof by saidelectro-magnet, and an electrical contact element engageable with acontact point on each of said main reeds during the forward movement ofone of the supplemental reeds and the retractile movement of the othersupplementalreed.

16. A compound reed mechanism, each mechanism comprising a main reed anda supplemental reed, means for supporting the main and supplementalreeds in superposed relation, an electro-magnet adapted to periodicallydraw each supplemental reed away from the free end of each main reed,the free end of each main reed engaging an intermediate portion of itssupplemental reed upon a retractile movement of said supplemental reedfollowing the attraction thereof by said electro-magnet, and an inertiaelement carried on each of said supplemental reeds and adjustablymovable longitudinally thereon to vary the periodicity thereof, and anelectrical contact element engageable with a contact point on each ofsaid main reeds during the forward movement of one of the supplementalreeds and the retractile movement of the other supplemental reed.

WILLIAM C. ROE.

